This invention relates to an orally administrable solid dosage form comprising a compacted ribavirin composition. The compacted ribavirin composition of this invention has an advantageously high tap density as well as surprisingly fast disintegration and dissolution rates and contains a freely flowing ribavirin of uniform physical characteristics which is substantially free of other polymorphic forms.
Ribavirin is an antiviral agent which is currently being administered in association with interferon alpha-2b to treat patients with chronic hepatitis C infections.
Ribavirin 200 mg capsules are manufactured and marketed by ICN Pharmaceuticals in Canada under the trade name Virazole.TM. capsules. The ribavirin used to make the ribavirin composition in the Virazole capsules is a non-freely flowing powder with low and variable tap densities in the range of 0.320 to 0.449 g/mL. A ribavirin composition with a tap density of at least 0.6 g/mL is needed for the uniform filling of the 200 mg capsules. It would be desirable for the ribavirin composition to have a uniformly high tap density of at least 0.6 g/mL to fill any capsule and to avoid excessive weight variation and excessive packing in the capsule shell during the capsule filling operation especially in the high speed capsule filling equipment which operate at a fill rate of over 20,000 capsules per hour.
Dry compacting of the ribavirin formulation would be an attractive solution to this problem so long as the heat produced during the compaction operation does not cause the formation of ribavirin polymorphic forms, which forms are unacceptable for obtaining health registration.
The Virazole capsules exhibited inconsistency in meeting the dissolution specifications which requires that 80% of the ribavirin be dissolved in water in 30 minutes. The disintegration times of the Virazole composition were typically around 20 minutes.
There is a need for a ribavirin composition with a tap density of at least 0.6 g/mL and having improved dissolution rates and reduced disintegration times. There is also a need to compact the ribavirin composition to achieve such high tap densities while maintaining the ribavirin in the physical state substantially free of polymorphic forms.